ALBANY — Gov. Cuomo’s once stratospheric approval ratings have hit a slide this year — and state Republicans are smelling blood.

GOP strategists have been talking with at least five potential 2014 Cuomo challengers.

Republican kingmakers have reached out to Westchester County Executive Rob Astorino, 2010 state comptroller candidate and investor Harry Wilson, Rep. Chris Gibson of the Hudson Valley, Dutchess County Executive and former state Assemblyman Marc Molinaro, and Chautauqua County Executive Greg Edwards, the 2010 GOP candidate for lieutenant governor.

“There have to be behind-the-scenes, quiet conversations, which I can tell you are ongoing,” a senior New York Republican strategist told The Post.

Controversy over the gun-control law Cuomo pushed through the Legislature in January following the Newtown, Conn., school massacre helped drive the first-term Democrat’s job approval ratings from 74 percent last December to 55 percent last month in Quinnipiac University polls.

The latest survey found him losing in the New York suburbs and upstate to GOP Gov. Chris Christie of New Jersey in a hypothetical presidential run.

Washington is also watching.

“The drop in Cuomo’s approval offers the chance for Republicans to seriously take him in this election,” said DC-based GOP political strategist Ron Bonjean, who previously served as a top aide to GOP leadership in the House and Senate. “It also has the potential of dragging Cuomo further into the political quicksand.”

The GOP believes Cuomo has begun making other politically exploitable missteps, including:

* Delaying a decision on whether to green-light the controversial, natural-gas drilling technique known as fracking, which has divided the state.

* Obtaining luxury seats for himself and top aides at the Buffalo Bills’ stadium in a deal to keep the state’s only NFL team from leaving.

* Cutting aid for the developmentally disabled and planning an election-year tax rebate for families while other taxes and fees increase.

But the New York strategist conceded Cuomo — with a war chest topping $22 million at last count — remains a formidable incumbent, and added that the GOP might run a 2014 candidate to build name recognition with an eye to winning in 2018.